Field of the Invention
The invention relates to a high-voltage DC/DC converter, and is preferably used in the field of high-voltage DC transmission (HVDCT).
A high-voltage DC distribution network with a feeder or feeders and a branch or branches are used in connection with high-voltage DC/DC converters. The two ends of the high-voltage DC distribution network are connected to a first converter and to a second converter respectively, with respective energy-storage capacitors, with an earthed center point, being provided in each case. The two converters respectively, have connections, respectively, on the other side for three-phase networks. The first converter is preferably used as a feeder rectifier, and for this purpose is connected to a power station. The second converter preferably operates as an inverter, for feeding into a branching supply network.
The high-voltage DC distribution network is furthermore connected to a third converter and to the high-voltage DC/DC converter. The third converter is provided on the other side with connections for a preferably low-voltage three-phase network, and may operate either as an inverter for feeding from the distribution network into the three-phase network, or as an inverter for feeding from the three-phase network into the high-voltage DC distribution network.
The high-voltage DC/DC converter is connected via connections to the distribution network, and has connections for a further preferably low-voltage (medium-voltage) DC network. First, it is possible to use the high-voltage DC/DC converter for feeding the DC network (for example a medium-voltage DC distribution network) from the high-voltage DC distribution network. Second, it is possible to use the high-voltage DC/DC converter for feeding the high-voltage DC distribution network from the DC network. In the latter case, the high-voltage DC/DC converter is connected, for example, to a solar power station or to a wind-driven power station.
It is accordingly an object of the invention to provide a high-voltage DC/DC converter which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which can be produced cost-effectively for various primary-side and secondary-side voltage requirements.
With the foregoing and other objects in view there is provided, in accordance with the invention, a high-voltage DC/DC converter. The high-voltage DC/DC converter has a number of primary-side converter modules having DC connections. The DC connections of the primary-side converter modules are connected in series between connections of a high-voltage DC distribution network. Each of the primary-side converter modules have a primary-side converter bridge, a primary-side capacitor connected to the primary-side converter bridge, a primary-side series resonant capacitor connected to the primary-side converter bridge, a transformer connected to the primary-side series resonant capacitor and to the primary-side converter bridge, and a secondary-side series resonant capacitor connected to the transformer. At least one secondary-side converter module having DC connections is provided. The DC connections of the secondary-side converter modules are connected in parallel between connections of a further DC network. The secondary-side converter module have a secondary-side converter bridge and a secondary-side capacitor connected to the secondary-side converter bridge.
The advantages that can be achieved by the invention are, in particular, that the proposed module concept allows the high-voltage DC/DC converter to be matched to the specified voltage of the high-voltage DC distribution network in a very simple and universal manner. That is to say the number of converter modules that need to be connected in series is governed by the voltage of the high-voltage DC distribution network. All that is required is to configure, manufacture and stock a very small number (for example three) of different types of converter modules (with different current, voltage and rating data) in order to allow all the conceivable variations in the field of high-voltage DC supply technology and branching technology to be covered.
Since the converter modules are produced in relatively large quantities, this results in cost advantages in comparison to a solution approach without using modules. The time penalty required to implement a project is considerably reduced, and spares stockholdings are simplified.
Advantageously, there is no need for any synchronized drive for a series circuit containing a large number of active semiconductor devices disposed between the high-voltage connections.
In accordance with an added feature of the invention, both the primary-side converter bridge and the secondary-side converter bridge have semiconductor switches which can be switched on and off actively.
In accordance with an additional feature of the invention, the primary-side converter bridge has a semiconductor switch which can be switched on and off actively, and the secondary-side converter bridge is formed of diodes.
In accordance with a further feature of the invention, the primary-side converter bridge is formed of diodes, and the secondary-side converter bridge includes semiconductor switches which can be switched on and off actively.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a high-voltage DC/DC converter, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.